The present invention relates on the one hand to an original of an information carrier, comprising a recording layer which has been applied to a carrier material and which contains a relief image reproducing the information. The relief image is composed of a plurality of relief part-images in one plane, which adjoin one another without overlapping and on which a relief grid of different grid depths is superposed in the areas of the individual relief part-images. In another aspect, the invention pertains to a process for preparing an original of this kind.
Images which are grid-wise screened are produced by the ZOD (Zero-Order-Diffraction) technique which is known from the journal, Laser u. Opto-Elektronik, No. 3/1976, pages 16/17. Three nickel matrices are produced from the relief images which, for example, correspond to three primary color grid patterns in yellow, magenta and cyan in three photo-lacquer layers, and these matrices are used to emboss colorless thermoplastic films of, for example, polyvinyl chloride. These films are mechanically superposed and, upon projection using conventional projectors, colored projection images are obtained from the colorless relief images. The grid-like screening is effected with relief grids of rectangular cross section, the grid period being about 1.5 .mu.m. One nickel matrix of different relief depth is made for each color separation in magenta, yellow and cyan, and the separate embossed images are generated using these matrices. The relief depths differ, the relief depth of the cyan separation being the greatest and that of the yellow separation being the smallest. These color separation images are screened. The embossed images are superposed to give a three-layer relief image, from which colored images can be projected. The technique described gives very bright color images of high resolution. The relief images can be duplicated relatively cheaply and rapidly by embossing.
A disadvantage which makes the acceptance of this technique more difficult is the expensive preparation process with three completely separate working steps for making the individual embossed relief images corresponding to the color separations. A further disadvantage is the mechanical composing of the three separate relief images in a true fit to give the composite image required for the colored projection.
A solution which overcomes these disadvantages has already been suggested in co-pending application, Ser. No. 861,491, filed Dec. 16, 1977 by Roland Moraw et al and entitled "Information Carriers, Method of Forming and Copying Said Carriers". According to this teaching, the relief image is composed from the relief part-images corresponding to the individual color separations in such a way that areas of different color, which can also be screen dots in the case of screened images, are located in one plane, with these areas of different color not intersecting but at most touching one another. Relief images of this type are very suitable for depicting two-dimensional multi-colored originals, such as graphical illustrations, in the form of relief grid structures in one plane.
The invention disclosed in the aforementioned application Ser. No. 861,491, incorporated herein by reference, utilizes three primary colors, which in general would not be adequate for a representation, identical to the original, of multi-colored originals containing secondary colors, for example multi-colored landscape images.